中文摘要：

贵州桐梓红花园山王庙的奥陶系-志留系分界地层出露好、有笔石带控制且发育介壳相化石,一直被认为是华南最佳剖面之一。本文对该剖面重新剖析,结合桐梓县境南区另外几条剖面的资料分析,提出如下新认识：山王庙剖面的＂赫南特贝层＂（HirnantiaBed：AFA295-305）和＂介壳层＂（Shelly Bed：AFA306-311c）宜合并统称为观音桥层,皆归于奥陶系;对照宜昌王家湾,将观音桥层与Normalograptus extraordinarius带上部和N.persculptus带下部对比;确定观音桥层与龙马溪组之间缺失N.persculptus带上部、A.ascensus带和P.acuminatus带大部分的地层。典型赫南特贝动物群延至A.ascensus带甚至更高层位的观点应予以修正。靠近黔中古陆北缘的诸多地点,观音桥层的厚度虽有变化,均宜视为同期沉积,唯上覆地层时代不同。赫南特贝动物群是在特定时期、特定环境中生存的特定底栖生物群落,是奥陶纪末大灭绝首幕后的产物,指示了寒凉、海退、相对浅水、底域富氧的环境条件,有重要的时代、环境和古地理意义。

英文摘要：

The Ordovician-Silurian boundary section at Shanwangmiao, Honghuayuan, southeast of Tongzi County Town was thought to be one of the best sections through the Ordovician-Silurian transition in China where the boundary rocks are well-exposed, continuous, and abundant with shelly fossils and the biostratigraphically impartant graptolites. On the basis of detailed investigation on the Shanwangmiao section together with several other sections in southern Tongzi, including the Nanbazi section of Honghuayuan, Sancha section of Maoba, and Daijiagou section of Liaoyuan, new interpretations of the boundary rocks at the Shanwangmiao section are proposed. The Kuanyinchiao Bed, i.e. the Hirnantia Bed （AFA295-305） and the Shelly Bed （AFA306-311c） should be combined as a single lithostratigraphical unit of Ordovician age as they have similar lithology and yield the same brachiopod fauna. Comparison with the basal boundary stratotype of the Hirnantian Stage at Wangjiawan, northern Yichang, shows that the Kuanyinchiao Bed at Shanwangmiao can be correlated with the upper Normalograptus extraordinarius Biozone and the lower N. persculptus Biozone. There is a hiatus between the Kuanyinchiao Bed and its overlying Lungmachi Formation （AFA312）, missing the upper N. persculptus Biozone, the Akidograptus ascensus Biozone, and most part of the Parakidograptus acuminatus Biozone. Thus, the recognition that the typical Hirnantia Fauna could extend to the earliest Silurian A. ascensus Biozone or even higher horizon in South China（Rong Jia-yu et al., 2002） is modified. The Kuanyinchiao Bed at many localities in Southwest China may be regarded as coeval rock units although its thickness is variable. The Hirnantia Fauna after the first episode of the end Ordovician mass extinction contains a series of unique benthic communities with special affinities, geologic age, and environmental background. It is not only age indicative, but also reflects sea water cooling, shallowing, and bottom oxygenation.